The film capacitor has, for example, a dielectric film obtained by forming a polypropylene resin into a film, and a metal film formed on a surface of the dielectric film by vapor deposition. The metal film is used as an electrode. With such a configuration, the film capacitor has an advantage that even when short-circuiting occurs in an insulation defect portion of the dielectric film, the metal film around the defect portion evaporates and scatters due to a short circuit energy, and the insulation defect portion is insulated, so that dielectric breakdown of the film capacitor can be prevented (self-recovery property).
In this manner, the film capacitor can prevent ignition and electric shock when an electric circuit is short-circuited. Focusing on this point, recently, the film capacitor has been applied to a power supply circuit such as LED (Light Emitting Diode) lighting and the like, and applications are expanding to motor drive of hybrid cars, an inverter system for solar power generation, and the like.
In the film capacitor, when the self-recovery property functions as described above, the metal film around the insulation defect portion evaporates and scatters for insulation. As a result, an area of the electrode for generating electrostatic capacitance is reduced and a capacitance of the film capacitor is reduced. In order to suppress reduction in capacitance after self-recovery, a film capacitor in which a deposition electrode in the vicinity of an insulation margin portion is divided into a plurality of small regions and these regions are connected in parallel by fuses is disclosed (see, for example, Patent Literature 1). In the film capacitor having such a structure, when the self-recovery property functions, the fuse is blown and the region having the defect portion can be separated from the electric circuit.